1. Field of the Invention
The present invention relates generally to tracking the location of a tangible object. More specifically, the present invention relates to a method, apparatus, and computer usable code to locate a desired medium.
2. Description of the Related Art
Evolving technologies allow products to be tagged with inexpensive radio frequency transponders and then tracked by devices that can read the information encoded into the radio frequency transponder, which is also referred to as a transponder. Radio frequency identification (“RFID”) uses low-powered radio transmitters to read data stored in a transponder at distances up to 200 feet away. Applications of this technology include tracking assets, managing inventory, automatic vehicle identification, highway toll collection, and authorizing payments.
Developers first made RFID systems in the 1940s. An initial application of the technology allowed the U.S. government to use transponders to distinguish between friendly and enemy aircraft. Air traffic controllers continue to use transponders for aircraft tracking. In addition to tracking aircraft, the commercial aviation industry has used RFID tags to route baggage and increase air security. In the 1970s, the U.S. government used RFID systems for tracking livestock and nuclear material. Recent applications allow a vendor to authenticate customers in order to pay for food or gas.
Commercial applications generally operate in unlicensed frequency bands, with 125 KHz and 13.56 MHz being the most common. The greater the bandwidth the more information a RFID tag can hold. For instance, a 13.56 MHZ tag can hold as much as 2,000 bits of data, roughly 30 times the information that may be transmitted using a 125 KHz tag. Active RFID tags are equipped with a battery that allows an active tag to transmit a signal to a reader. These tags often provide the greatest range, up to 200 feet, but are more expensive than other tags. Passive RFID tags are not battery powered. Instead, this type of device draws power from the electromagnetic waves emitted from the receiver-transmitter or RFID reader. The read range of these tags is generally under three meters. Semi-passive RFID tags have batteries like active RFID tags, but the battery is only used to power the tag's microchip circuitry. Semi-passive tags also have longer read ranges than passive tags.
One example of RFID use is inventory control, wherein items include attached RFIDs. Up to 2,000 bits of data are stored on a memory chip constructed in a button or integrated circuit card. Some tags include etching on a substrate, embedded in a paper or plastic tag. The information stored on the tag may include a unique product identification code, the place of product manufacture, and the place of sale. The tag may include a battery or it may be passive.
A RFID transmitter-receiver or reader generally includes a transmitter, a receiver and a digital control module connected to a transmitting antenna. The reader interrogates RFIDs, receives a response, and decodes the data. The reader passes that data on to a host system. The host system assimilates the data received from the product tags. The host system often provides reports used to track product inventory and sales.